Line up the green beans on a chopping board and cut off the stalks.
Put the beans in a sauce pan of boiling water with a dash of salt and cook for about six minutes. Drain, reserving some of the cooking water, and set them aside to steam dry.
Put the pan back on the heat, add the oil and the garlic. Stir. When the garlic starts to turn golden, add the beans and shake them around in the pan to coat them in the garlic oil.
Add a small ladleful of the reserved cooking water, the parmesan cheese, and the lemon juice. Stir and simmer until the water and cheese start to form an oozy, sticky sauce. Remove from the heat and serve immediately.